A variety of automatic wire-tying machines have been developed, such as those disclosed in U.S. Pat. No. 5,027,701 issued to Izui and Hara, U.S. Pat. No. 3,889,584 issued to Wiklund, U.S. Pat. No. 3,929,063 issued to Stromberg and Lindberg, U.S. Pat. No. 4,252,157 issued to Ohnishi, and U.S. Pat. No. 5,746,120 issued to Jonsson. The wire-tying machines disclosed by these references typically include a track that surrounds a bundling station where a bundle of objects may be positioned, a feed assembly for feeding a length of wire about the track, a gripping assembly for securing a free end of the length of wire after it has been fed about the track, a tensioning assembly for pulling the length of wire tightly about the bundle of objects, a twisting assembly for tying or otherwise coupling the length of wire to form a wire loop around the bundle of objects, a cutting assembly for cutting the length of wire from a wire supply, and an ejector for ejecting the wire loop from the machine.
One drawback to conventional wire-tying machines is their complexity. For example, a variety of elaborate hydraulically-driven, or pneumatically-driven actuation systems are commonly used for performing such functions as securing the free end of the length of wire, for cutting the length of wire from the wire supply, and for ejecting the wire loop from the machine. Track assemblies also typically require some type of spring-loaded hydraulic or pneumatic system to actuate the track between a closed position for feeding the wire about the track, and an open position for tensioning the wire about the bundle of objects.
Such hydraulic or pneumatic actuation systems require relatively expensive cylinder and piston actuators, pressurized lines, pumps, valves, and fluid storage facilities. These components not only add to the initial cost of the wire-tying machine, but also require considerable maintenance. The handling, storage, disposal, and cleanup of fluids used in typical hydraulic systems also presents issues related to safety and environmental regulations.